Abstract : Solid-state electronics is now at the threshold of the era of microelectronics. The salient feature of microelectronics is integration typified by the functional device. A functional device consists of an interconnected array of conventional devices--transistors, diodes, capacitors, and resistors--fabricated in situ within a single crystal of silicon, with the capability of performing a complete electronic circuit function. The most promising applications of functional devices are in digital circuits and systems where they provide potential reliability, cost, size, and weight advantages over conventional circ it techniques. (Author)